A ball bearing is a type of rolling-element bearing that uses balls to maintain the separation between two elements, commonly referred to as the bearing races, or sometimes referred to as an outer ring and an inner ring. A ball bearing is used to reduce rotational friction between two or more elements and to support radial and axial loads. A ball bearing uses at least two races to contain the balls and transmit the loads through the balls. In most applications, one race is stationary and the other race is attached to a rotating assembly, such as a hub or shaft. As one of the bearing races rotates, the rotational movement causes the balls to rotate as well. With the balls in a rolling orientation, the balls have a much lower coefficient of friction as compared to the two race surfaces sliding against each other. Bearing balls tend to have lower load capacity for their size than other kinds of rolling-element bearings due to the smaller contact area between the balls and races.
A common construction type of ball bearings are those that have their balls evenly spaced and separated by a cage. A prior art ball bearing assembly 10 is illustrated in FIGS. 1 and 2. This conventional ball bearing type is a Conrad-style ball bearing. In this style, bearings are assembled by placing an inner ring 14 into an eccentric position relative to an outer ring 12, such as in FIG. 2. The two rings 12, 14 may contact at one point, resulting in a large gap opposite the point of contact. In this or similar positions, the balls 20, 22, 24, 26, 28, 30, 32 may be inserted through the gap and then evenly distributed around the bearing assembly, causing the rings to become concentric, such as in FIG. 1. The assembly 10 is completed by fitting a cage to the balls to maintain their positions relative to each other. Without the cage, the balls would eventually drift out of position during operation, causing the bearing to fail. The cage carries no load and serves only to maintain ball position. It should be understood that other Conrad ball bearings exist with one or more similar features.
Conrad bearings have the advantage that they are able to withstand both radial and axial loads, but have the disadvantage of lower load capacity due to the limited number of balls that can be loaded into the bearing assembly. However, due to this loading method and the use of a cage, the assembly will include additional space between the balls and thus the maximum amount of balls that can fit in the ball bearing is reduced to allow room for assembly and the cage.
In order to increase the radial load capacity of a bearing, the bearing can be a full complement bearing or fully loaded without the use of a cage. Another prior art ball bearing assembly 40 is illustrated in FIG. 4. Typical ball loading methods for balls in a full complement ball bearing require a groove 50, 52 in the inner ring 44 and/or outer ring 42 to the load the balls, such as shown in FIG. 3. Due to this structure, the ball bearing 40 is not fit to withstand axial loads as the balls can pop out of the groove. It should be understood that other full complement ball bearings exist with one or more similar features.
Generally, an angular contact ball bearing uses axially asymmetric races. An axial load passes in a straight line through the bearing, whereas a radial load takes an oblique path that tends to want to separate the races axially. In this construction, the angle of contact on the inner race is the same as that on the outer race. Angular contact bearings better support so-called combined loads, that is loading in both the radial and axial directions.
Single row angular contact bearings can only be loaded axially in one direction. For them to be fit to be used in both directions, a second bearing will need to be paired with the first or a double row angular contact bearing can be used. Double row angular contact bearings include two rows of bearings loaded in a face to face or back to back configuration which allow for the bearing to be loaded in both directions. FIG. 4 is an enlarged cross-sectional view of a portion of a prior art ball bearing assembly 60 in which bearing balls may be loaded in two directions. It should be understood that other double row angular contact ball bearing exist with one or more similar features.